A combined compression and indentation study of mechanical metamaterials based on inverse opal coatings
A combined compression and indentation study of mechanical metamaterials based on inverse opal coatings
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DOI：
10.1016/j.actamat.2020.04.025
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发表时间：
2020-08-15
期刊：
影响因子：
9.4
通讯作者：
Lilleodden, Erica T.
中科院分区：
文献类型：
--
作者：
do Rosario, Jefferson J.;Haentsch, Yen;Lilleodden, Erica T.
一种基于反蛋白石（IO）结构的相对较新的定制光子超材料由于其周期性多孔拱形结构而显示出多功能性和出色的机械响应。通过改变孔径和添加原子层沉积 (ALD) 薄膜，利用越小越强的范例，实现可定制的强度和弹性模量。这些特性的量化是通过平冲纳米压痕测试来实现的。通过与微压缩测试进行比较来验证结果，微压缩测试是一种广泛使用的技术，用于规避通常由压痕施加的复杂应力状态，但在高孔隙率的情况下被大大简化，近似于单轴应力；两种机械加载方法的结果显示出很强的相似性。所有结果都表明强度和弹性模量依赖于变形尺寸（即微柱或平冲头直径）与孔径的比率，这一趋势可以通过测试方法的边界条件的影响而不是内在的尺寸效应来很好地描述。在较大的比率下，这些值接近恒定值。此外，可以通过在二氧化硅IO结构的壳结构上沉积薄膜来定制机械响应； 34 nm 的 TiO2 可使强度增加 10 倍，弹性模量增加 5 倍。 (C) 2020 Acta Materialia Inc. 由 Elsevier Ltd 出版。
A relatively new class of tailored photonic metamaterials based on the inverse opal (IO) structure shows multifunctionality with exceptional mechanical response due to its periodic porous arch-like structure. Exploiting the smaller is stronger paradigm through varying its pore size and the addition of atomic layer deposition (ALD) films, allow tailorable strength and elastic modulus. Quantification of such properties are achieved through flat punch nanoindentation testing. Results are validated by comparison to microcompression tests, a widely used technique to circumvent the complex stress state normally imposed by indentation, but in the case of high porosity is greatly simplified, approximating uniaxial stress; results from both mechanical loading approaches show strong similarities. All results showed a dependence of strength and elastic modulus on the ratio of the deformation size, i.e., micropillar or flat punch diameter, to the pore size, a trend which is well described by the influence of the boundary conditions of the test method rather than an intrinsic size effect. At larger ratios the values approach a constant value. Furthermore, the mechanical response can be tailored through the deposition of a thin film on the shell structure of the silica IO structures; 34 nm of TiO2 was shown to produce a 10-fold increase in strength and 5-fold increase in elastic modulus. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd.